Mexican authorities said they are investigating the possible murder of Raul Hernandez, whose body was found beaten and with a head injury possibly caused by a sharp object.
Local media reported Hernandez was found in the early hours of Saturday, in the Ocampo municipality, about 8km from the Monarch Butterfly Biosphere Reserve.
Hernandez was reported missing by his family on 27 January after he left his home in the town of San Pedro Libertad, said the state prosecutor in a statement.
His disappearance and ensuing death sparked an outcry in Mexico, where environmental and human rights activists are routinely threatened or even killed as a result of their work.
Gonzalez, who fought to defend the monarch butterfly’s wintering grounds from illegal logging, managed the El Rosario butterfly sanctuary located inside the Monarch Butterfly Biosphere Reserve.
Millions of monarch butterflies make a mammoth 2,000-mile journey every year from Canada to central Mexico to escape winter.
However, their survival is endangered by threats to their habitat, caused by climate change and illegal logging.
The Michoacan Human Rights Commission urged authorities to investigate if Gonzalez’s disappearance was connected to illegal loggers, reported Mexico News Daily.
“He is probably hurting the [business] interests of people illegally logging in the area,” said Mayta Cardona, an official at the commission.
Michoacan state houses the largest monarch butterfly reserve in Mexico, which is now a Unesco World Heritage site. It is also home to rival drug gangs who fight to control smuggling routes through the Mexican interior, often leading to violent deaths.